The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Hybrid powertrains typically include a first torque generator, such as an internal combustion (ICE), and a second torque generator, such as an electric machine (EM). Both may provide torque to a driveline to propel a vehicle. In a full hybrid powertrain, the EM may drive the drivetrain directly, without transferring torque through a component of the ICE. In a mild hybrid powertrain, the EM may be coupled with the ICE through the accessory drive, and torque generated by the EM is transferred to the drivetrain through the ICE. An exemplary mild hybrid powertrain includes a belt alternator starter (BAS) system. In the BAS system, the EM is coupled to the ICE via a belt and pulleys. Other accessory components, such as pumps and compressors, may be powered by the belt or additional belts attached to one of the pulleys. Alternatively, the other accessory components may be driven by electric power.
Referring now to FIG. 1, a functional block diagram of a hybrid powertrain of a vehicle is presented. The hybrid powertrain includes an internal combustion engine (ICE) 102, a motor generator unit (MGU) 104, an inverter 106, a hybrid battery 108, and an accessory power module (APM) 110. The APM 110 provides power to a 12V battery 114 and 12V vehicle loads 116.
The inverter 106 converts power between the DC voltage of the hybrid battery 108 and the electrical power produced by the MGU 104. The DC voltage of the hybrid battery 108 may be 42 volts in the current hybrid systems and may be 118 volts in the next generation of BAS hybrids. The APM 110 converts power from the DC voltage of the hybrid battery 108 into a standard vehicle voltage, such as 12 volts. By using the APM 110, the 12V vehicle loads 116 do not need to be redesigned to work with the higher voltage of the hybrid battery 108.
The ICE 102 and the MGU 104 may be coupled via a belt 120 encircling pulleys 122 and 124 of the ICE 102 and the MGU 104, respectively. The combined torque of the ICE 102 and the MGU 104 propel the vehicle. When more propulsion torque is desired than the ICE 102 is currently producing, the MGU 104 may be used as a motor to provide additional torque.
At times when the ICE 102 is producing more torque than is required, the MGU 104 may function as a generator, providing power to the hybrid battery 108. In addition, during regenerative braking, the MGU 104 may function as a generator, slowing the vehicle while providing electrical power to the hybrid battery 108.